The objectives of this project are to participate in the current and proposed extended protocols and addenda studies of the Cooperative Breast Cancer Group with goals of improving the quality and rate of regression of patients with metastatic breast cancer. Participation in the Group Studies provides a comparable basis for patient evaluation, a rapid extension of promising therapeutic approaches and a means for comparing host-tumor interactions studied in this institution with observations made elsewhere. Levels of serum pituitary hormones (growth hormone, thyroid stimulating hormone, follicle stimulating hormone, luteinizing hormone and prolactin) will be measured. Tissue cultures of human breast cancer will be made and the in vitro cytotoxic effects of drugs will be investigated. Immunologic studies and estrogen receptor studies will be performed according to the Cooperative Breast Cancer Group protocols.